1. Field of the Invention
The present invention relates to methods and apparatuses for evaluating NVH characteristics in general, and more particularly to method and apparatus for experimentally evaluating at least one of NVH characteristics of a mechanical system including a torque-transmitting assembly having a drive member and a driven member drivingly engaging said drive member.
2. Description of the Prior Art
Implementation of modern technologies for analysis of noise, vibration and harshness (NVH) problems in the automotive field can encounter certain problems, one of which is the lack of objective criteria of noise and/or vibration acceptance in terms of its technological background. In other words, there is no clear correlation between some of critical technical parameters of automotive systems and overall noise level associated with them. Conceptual understanding of their functional connection does not achieve objective of a quantified association through a reliable and repeatable measurement methodology. Evaluation of NVH parameters of automotive axles in association with motion transmission errors (MTE or TE) in hypoid gear sets (final drives) of the axles could be considered as an example of such methodology. Similar methods could be used in application to any other driveline components of a motor vehicle.
It is known in the art that there is a correlation between TE of automotive axle and level of noise associated therewith in a passenger compartment of a motor vehicle. However, currently there exists no quantitative evaluation of such an association. As a result, automotive engineers and manufacturers of the automotive driveline components are forced to produce driveline components, such as drive axles, with maximum accuracy to insure that noise generated by the driveline components does not exceed established level. Consequently, the driveline component manufacturers tend to over-engineer their products, which, as a result, cost much more than it is necessary. In fact vehicle manufacturers' requirements could be satisfied with substantially less production accuracy and cost associated therewith.
With this in mind, a need exists to develop a method and apparatus for objectively and quantitatively evaluating NVH characteristics of a mechanical system transmitting torque from a drive member and a driven member associated with their manufacturing accuracy in order to determine necessary production accuracy threshold.